A vortex evaporator is a type of evaporator which moves one or more containers having a solvent and solid solution contained therein in an orbital motion to cause the solution to form a vortex configuration. The vortex increases the surface area of the solution which increases the evaporation rate of the solvent from the solid so that the solvent can be separated from the solid.
An example of such an evaporator is shown in U.S. Pat. No. 3,944,188 to Parker et al. The evaporator shown therein combines a vortexing motion, heat, and a vacuum to increase the evaporation rate of the solvent from the solid. The vacuum comprises is drawn by a vacuum pump that generates a controlled vacuum within the chamber of the vortex evaporator. The vacuum reduces the boiling point of the solvent and solid solution, thereby permitting evaporation to occur at a lower temperature than would be possible under atmospheric conditions.
However, vacuum pumps require a vacuum trap to catch the evaporation vapors from the chamber of the vortex evaporator and a condenser to condense such vapors before they enter the pump. A significant limitation of vacuum pumps is that the valves are readily destroyed if excessive vapors overload the trap. Thus, vacuum evaporators are not cost effective at higher evaporation rates. Freezer traps can be employed to overcome this limitation. However, such traps are prohibitively expensive.
A further problem associated with prior art vortex evaporators is that the heaters for the evaporators were located outside of the evaporation chamber. The heat was transferred to the chamber via a transferable medium, such as an aluminum block, which formed part of the chamber wall. Such an arrangement was not very efficient because the heat was not directly supplied to the chamber of the vortex evaporator. Further, it was difficult to determine the temperature within the chamber because knowledge of the heater temperature did not provide an accurate measurement of the actual heat transferred to the chamber through the chamber wall. It would have certainly been more efficient to locate the heater within the chamber of the vortex evaporator to thereby directly supply heat to the chamber. However, the wires of the heater required a means of feeding the wires of the heater from the power supply located outside of the chamber to the heater within the chamber without affecting the vacuum. Known means of accomplishing that result were prohibitively expensive.
Yet another problem associated with prior art vortex evaporators is that a comprehensive and efficient control system has not been implemented to control operation of the vortex evaporator. Thus, accurate measurement of heat within the chamber was not directly measurable. Further, it would also be desirable to locate liquid level sensors within the chamber of the evaporator to determine the liquid or solvent level within each container. Such measurement devices required electrical connections from the control system located outside of the chamber to the sensors located within the chamber, and therefore suffer from the problem described above for heaters.
A further problem with prior art evaporators is that the rubber isolators used to smooth or dampen the orbital motion of the holder were only operable for a limited time. First, the rubber isolators are highly susceptible to many of the chemicals spilled or otherwise present in the chamber. Second, a metal plate at the top of the isolators frequently pulls out, rendering the isolators inoperable. Third, the use of isolators results in relatively high consumption of electrical power to provide the desired motion.